Operating GPS receivers in GPS-adverse environment

ABSTRACT

A system for operating a GPS receiver in a GPS-adverse environment includes a plurality of GPS receivers, a plurality of remote sensor interfaces (RSIs), and a computer management system. The GPS receivers are adapted to determine positional parameters based on the GPS satellite signals. A first set of GPS receivers is able to accurately determine its positional parameters and a second set of GPS receivers is unable to do so. Each RSI is associated with a respective GPS receiver. The RSIs are communication nodes in an ad hoc wireless network. The computer management system identifies a GPS receiver that is not accurately determining its positional parameters, and in response, causes GPS information to be provided from one of the first set of GPS receivers to the identified GPS receiver. The identified GPS receiver then determines its positional parameters accurately using the provided GPS information.

I. CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a nonprovisional of, and claims priorityunder 35 U.S.C. § 119(e) to Twitchell et al., U.S. Provisional PatentApplication No. 60/595,233 filed Jun. 16, 2005. The entire disclosure ofthis patent application is hereby incorporated herein by reference.

II. INCORPORATION BY REFERENCE

The present application hereby incorporates by reference: Twitchell U.S.Pat. No. 6,745,027 B2 (titled “Class Switched Networks for TrackingArticles”); Twitchell International Patent Application Publication No.WO 03/032501 A2, which international patent application designated theUnited States and was published in English (titled “Network Formation inAsset-Tracking System Based on Asset Class”); Twitchell InternationalPatent Application Publication No. WO 03/098851 A1, which internationalpatent application designated the United States and was published inEnglish (titled “LPRF Device Wake Up Using Wireless Tag”); TwitchellU.S. Patent Application Publication No. 2005/0093703 A1 (titled “Systemsand Methods Having LPRF Device Wake Up Using Wireless Tag”); TwitchellU.S. Patent Application Publication No. 2005/0093702 A1 (titled“Manufacture of LPRF Device Wake Up Using Wireless Tag”); and TwitchellU.S. Patent Application Publication No. 2004/0082296 A1 (titled “NetworkFormation in Asset-Tracking System Based on Asset Class”).

III. COPYRIGHT STATEMENT

All of the material in this patent document is subject to copyrightprotection under the copyright laws of the United States and othercountries. The copyright owner has no objection to the facsimilereproduction by anyone of the patent document or the patent disclosure,as it appears in official governmental records but, otherwise, all othercopyright rights whatsoever are reserved.

IV. BACKGROUND OF THE INVENTION

Satellite navigation systems, such as the system commonly known as theGlobal Positioning System (“GPS”), operated by the United StatesDepartment of Defense, are well known. Satellite navigation systems areused for determining a precise location almost anywhere on Earth. Inparticular, GPS can be used by anyone, free of charge, to make suchdeterminations. For this reason, among others, satellite navigationsystems are generically referred to hereinafter as GPS.

GPS is divided into three segments: space, control, and user. The spacesegment comprises the GPS satellite constellation. The control segmentcomprises ground stations around the world that are responsible formonitoring the flight paths of the GPS satellites, synchronizing thesatellites' onboard atomic clocks, and uploading data for transmissionby the satellites. The user segment consists of GPS receivers used forboth military and civilian applications.

The GPS system uses a satellite constellation of at least 24 activesatellites orbiting about 20,000 km above the Earth. Each satellitemakes a complete orbit of the Earth every 12 hours. Satellite positionsare carefully calculated so that, from any point on the Earth, four ormore of the satellites will be in direct line of sight to any location.Each satellite carries four atomic clocks so that the transmission timeof the signals is known precisely. The flight paths of the satellitesare measured by five monitor stations around the world. A master controlstation processes their combined observations and sends updates to thesatellites through monitor stations. The updates synchronize the atomicclocks on board each satellite to within one microsecond and also adjustthe ephemeris of the satellites' internal orbital model to match theobservations of the satellites from the ground.

GPS receivers calculate their current position, i.e., latitude,longitude, elevation, and the precise time using the process oftrilateration. Trilateration involves measuring the distance to at leastfour satellites by comparing the satellites' coded time signaltransmissions. The receiver calculates the orbit of each satellite basedon information encoded in its radio signal and measures the distance toeach satellite based on the time delay from when the satellite signalwas sent until it was received.

Once the location and distance of each satellite is known, the receivershould theoretically be located at the intersection of four imaginaryspheres, one around each satellite, with a radius equal to the timedelay between the satellite and the receiver multiplied by the speed ofthe radio signals.

In practice, GPS calculations are more complex for several reasons. Onecomplication is that GPS receivers do not have atomic clocks, so theprecise time is not known when the signals arrive. Fortunately, even therelatively simple clock within the receiver provides an accuratecomparison of the timing of the signals from the different satellites.The receiver is able to determine exactly when the signals were receivedby adjusting its internal clock (and therefore the spheres' radii) sothat the spheres intersect near one point.

GPS is used for both military and civilian purposes. The primarymilitary purposes are to allow improved command and control of forcesthrough improved location awareness and to facilitate accurate targetingof smart bombs, cruise missiles, or other munitions. Civilians use GPSfor location determination and navigation purposes. Low cost GPSreceivers are widely available, combined in a bundle with a PDA or carcomputer. As such, the GPS system is used as a navigation aid inairplanes, ships and cars. The GPS system can also be used by computercontrolled harvesters, mine trucks and other vehicles.

GPS signals can be affected by multipath issues, where radio signalsreflect off surrounding terrain such as buildings, canyon walls, hardground, etc. causing delay in when a signal reaches a receiver. Thisdelay causes inaccuracy in position location. Multipath issues areparticularly present in urban environments where a significant amount ofobstructions are present. A variety of receiver techniques have beendeveloped to mitigate multipath errors. For long delay multipath, thereceiver itself can recognize the wayward signal and discard it. Toaddress shorter delay multipath due to the signals reflecting off theground, specialized antennas may be used. However, this form ofmultipath is harder to filter out as it is only slightly delayed ascompared to the direct signal, thus causing effects almostindistinguishable from routine fluctuations in atmospheric delay.

Additionally, successful transmission of radio signals, including GPSsignals, may be disrupted through the use of jamming technology. Devicesmaking use of such technology, often referred to as “jammers,” can causenavigation and communication problems for radio signal receivers. Radioreceivers can be jammed in simple ways, such as by transmitting radiofrequency noise in the frequency spectrum in which the receiveroperates. More sophisticated jammers use various techniques to alterradio signals like those being sent from satellites. Such techniques mayinclude trying to attack modulation schemes, fooling a receiver intolocking onto incorrect radio signals, or mixing signals that inhibit areceiver from demodulating the data of the signal. As used herein, theterm “GPS deniers” or “GPS denial devices” shall generally refercollectively to GPS jammers, GPS repeaters (devices that rebroadcast orrepeat GPS signals or GPS-like signals, thereby creating confusion forGPS receivers), GPS interrupters (devices that use such techniques ascrossover bands and disruptive cancellation to interrupt GPS radiosignals from the GPS satellites), and all other devices that are or maybe used to disrupt reliable operation of GPS receivers.

GPS is particularly vulnerable to signal disruption because GPSreceivers are extremely sensitive. The receivers have to be sensitive toreceive relatively weak signals from orbiting satellites. A relativelylow-powered jammer, transmitting on the GPS frequency band, canoverpower legitimate GPS signals over a wide area—as much as a 100kilometer circle at just 1 watt radiated power. GPS receivers are sosensitive that there have been documented situations of unintentionaljamming. In one such situation three separate jamming signals were beinggenerated by VHF/UHF television antenna preamplifiers. The signals fromthe preamplifiers were strong enough to completely jam GPS within aone-kilometer radius at sea level.

Because the U.S. military relies heavily on GPS for locationdetermination, the vulnerability of military GPS receivers to beingintentionally jammed is particularly critical. GPS jammers and other GPSdenial devices may be used to deny signal acquisition and/or confuse aGPS receiver into giving erroneous results. Preventing the denial of GPSto troops in the field is potentially crucial in preventing causalitiesand carrying out successful military operations. Further exacerbatingthe problem is the fact that GPS denial devices are difficult to detectand find. Accordingly, a system for detecting and/or locating suchjammers is needed.

A related problem pertains to the use of jamming technology against anadversary while minimizing the effects of such use on one's own GPSreceivers. More specifically, jamming technology is often difficult tocontrol, affecting friendly GPS receivers the same way as adversarialGPS receivers. If GPS jamming technology is being used anywhere in thevicinity, by a friendly party or an adversarial party, it may not bepossible to rely on one's GPS receivers, thus requiring friendly forcesto operate with reduced accuracy or, perhaps worse, to operate under theimpression that their GPS information is accurate when in fact it isnot. Accordingly, a need exists for means to control the use of friendlyGPS jamming technology such that the effects of the friendly GPS jammerson one's own GPS receivers are minimized and/or localized.

The foregoing issues highlight a further, over-arching problem, whichrelates to the need for an easily-deployable system capable of jamming,on a controllable, localized level, enemy GPS receivers while predictingareas in which friendly GPS receivers may be used safely. Moreparticularly, the latter problem requires the ability to identifyjamming effects caused by both enemy GPS jammers and friendly GPSjammers.

V. SUMMARY OF THE INVENTION

The present invention includes many aspects and features.

In a first aspect of the invention, a system for detecting a GPS denialdevice includes: a plurality of GPS receivers for receiving radiosignals from GPS satellites, wherein each of the plurality of GPSreceivers determines parameters based on the signals received from theGPS satellites, the parameters including positional parameters; aplurality of remote sensor interfaces, each remote sensor interface ofthe plurality of remote sensor interfaces being associated with arespective GPS receiver of the plurality of GPS receivers such that eachremote sensor interface extracts the GPS parameters from a respectiveGPS receiver, wherein the plurality of remote sensor interfaces arecommunication nodes in an ad hoc wireless network; a gateway, serving asa communication node in the ad hoc wireless network, that receives theextracted GPS parameters from one or more of the plurality of remotesensor interfaces; and a computer management system, disposed incommunication with the gateway, that receives the extracted GPSparameters from the gateway and compares the determined GPS parameterswith historical GPS parameters for the plurality of GPS receivers todetect whether an active GPS denial device is present in the vicinity ofthe system.

In a feature of this aspect, the parameters determined by the pluralityof GPS receivers include positional parameters. The positionalparameters may include latitude and longitude, and the may includenon-positional GPS parameters, such as parameters pertaining to one ormore GPS signals.

In another feature of this aspect, each GPS receiver of the plurality ofGPS receivers is directly associated with a respective remote sensorinterface of the plurality of remote sensor interfaces. Each GPSreceiver and the respective remote sensor interface with which it isdirectly associated may be integrated into a unitary component containedwithin a single housing, or each GPS receiver and the respective remotesensor interface with which it is directly associated may be physicallyseparated from one another and contained in different housings. Each GPSreceiver and the respective remote sensor interface with which it isdirectly associated may be connected wirelessly, or each GPS receiverand the respective remote sensor interface with which it is directlyassociated may be connected by way of a cabled connection.

In yet another feature of this aspect, at least one remote sensorinterface of the plurality of remote sensor interfaces includes astandards based radio. Further, the at least one remote sensor interfacemay include a Wake-Up Receiver. The Wake-Up Receiver is adapted receivea wireless wake-up signal and to activate the standards based radio inresponse thereto, and the gateway includes a Wake-Up Transmitter that isadapted to transmit a wireless wake-up signal to activate the standardsbased radio. Further, the gateway includes a standards based radioadapted to communicate with the standards based radio of the at leastone remote sensor. The standards based radio of the at least one remotesensor is adapted to communicate with the gateway via other remotesensor interfaces using hopping.

In still another feature, the computer management system includes atleast one server. The server may be physically co-located with thegateway, or the at least one server may be a central servercommunicatively connected to the gateway via an external network.

In still another feature, the system further includes a GPS denier,associated with one of the remote sensor interfaces, for disruptingreliable operation of GPS receivers. The GPS denier is adapted to beselectively activated. The GPS denier is associated with the remotesensor interface such that the remote sensor interface effectuates theactivation of the GPS denier. The gateway communicates instructions tothe remote sensor interface with which the GPS denier is associated inorder to selectively activate the GPS denier. The computer managementsystem controls the instructions communicated by the gateway, therebyselectively controlling the activation of the GPS denier.

In a second aspect of the invention, a method for detecting a GPS denialdevice includes: receiving radio signals from GPS satellites;determining GPS parameters based on the received radio signals;transmitting the parameters; and comparing determined GPS parameters tohistorical GPS parameters to detect the presence of a GPS denial device.

In a feature of this aspect, the method further includes the step ofproviding a plurality of GPS receivers that each carry out the steps ofreceiving radio signals from GPS satellites and determining GPSparameters based on the received radio signals. The method furtherincludes the step of providing a plurality of remote sensor interfacesthat each carry out the step of transmitting the parameters. The step ofproviding a plurality of remote sensor interfaces may include the stepof providing a plurality of remote sensor interfaces that each include astandards based radio that carries out the step of transmitting theparameters, and may include a step of providing a plurality of remotesensor interfaces includes associating each remote sensor interface witha respective GPS receiver.

In another feature of this aspect, the step of transmitting theparameters includes transmitting the parameters via an ad hoc wirelessnetwork. Additionally, the method further includes the steps of:receiving the transmitted parameters at a gateway; and communicating thereceived parameters from the gateway to a computer management system.The step of communicating the received parameters to a computermanagement system includes communicating the received parameters via anexternal network.

In a third aspect of the invention, a method of determining the locationof a GPS denial device includes: in an area of interest, deploying aplurality of GPS receivers, each interfaced with a respective remotesensor interface, the remote sensor interfaces being communication nodesin an ad hoc wireless network; relaying GPS parameters from theplurality of GPS receivers to a computer management system via the adhoc wireless network; assessing the relative accuracy of GPS parametersdetermined by at least two of the plurality of GPS receivers, theaccuracy of the GPS parameters of one of the at least two GPS receiversbeing significantly greater than the accuracy of the GPS parameters ofthe other of the at least two GPS receivers; and determining at least anapproximate direction, relative to one or more of the at least two GPSreceivers, in which a GPS denial device is likely to be located, thedetermination being based on the relative accuracies of the at least twoGPS receivers.

In a fourth aspect of the invention, a system for operating a GPSreceiver in a GPS-adverse environment includes: a plurality of GPSreceivers for receiving radio signals from GPS satellites, wherein eachof the plurality of GPS receivers is adapted to determine parameters foritself based on the signals received from the GPS satellites, theparameters including positional parameters, wherein at least one of theGPS receivers, defining a first set of GPS receivers, is able toaccurately determine its positional parameters and at least one other ofthe GPS receivers, defining a second set of GPS receivers, is unable todetermine its positional parameters accurately; a plurality of remotesensor interfaces, each remote sensor interface of the plurality ofremote sensor interfaces being associated with and in electroniccommunication with a respective GPS receiver of either the first set orsecond set of GPS receivers such that each remote sensor interface isadapted to extract the GPS parameters from a respective GPS receiver,wherein the plurality of remote sensor interfaces are communicationnodes in an ad hoc wireless network such that each of said plurality ofremote sensor interfaces is in electronic communication with the otherremote sensor interfaces of the plurality of remote sensor interfaces;and a computer management system that identifies a GPS receiver that isnot accurately determining its positional parameters, and in response,causes GPS information to be provided from a selected GPS receiver inthe first set of GPS receivers to the identified GPS receiver; wherebythe identified GPS receiver is adapted to determine its positionalparameters accurately using the at least the GPS information providedfrom the selected GPS receiver in the first set of GPS receivers.

In a feature of this aspect, the computer management system isco-located with identified GPS receiver at the remote sensor interfaceassociated therewith.

In another feature of this aspect, the computer management system isco-located with selected GPS receiver, of the first set of GPSreceivers, at the remote sensor interface associated therewith.

In yet another feature of this aspect, the computer management system islocated remotely from the remote sensor interfaces.

In still another feature of this aspect, the system further includes agateway, serving as a communication node in the ad hoc wireless network,that is adapted to receive the extracted GPS parameters from one or moreof the plurality of remote sensor interfaces. Additionally, the computermanagement system is co-located with the gateway.

In still another feature of this aspect, the computer management systemis adapted to identify the GPS receiver that is not accuratelydetermining its positional parameters by receiving the extracted GPSparameters from the identified receiver and comparing the determined GPSparameters with historical GPS parameters for the identified GPSreceiver.

In still another feature of this aspect, the GPS information includes atleast one of Ephemeris information, Almanac information, GPS timeinformation, approximate location information, and information on GPSsatellites that should be in view of the identified GPS receiver.

In still another feature of this aspect, each remote sensor interfaceincludes a standards based radio adapted for transmitting and receivingthe GPS information. Additionally, the at least one remote sensorinterface includes a Wake-Up Receiver, and the Wake-Up Receiver isadapted receive a wireless wake-up signal and to activate the standardsbased radio in response thereto.

In a fifth aspect of the invention, a method for determining a locationof a GPS receiver in a GPS-adverse environment includes: providing aplurality of GPS receivers, each interfaced with a respective remotesensor interface, the remote sensor interfaces being communication nodesin an ad hoc wireless network; determining the locations of a first setof GPS receivers using radio signals received from GPS satellites;communicating GPS information, via the ad hoc wireless network, from oneor more GPS receiver of the first set of GPS receivers to an identifiedGPS receiver that is unable to determine GPS parameters from GPS radiosignals received from GPS satellites; and determining the locations ofthe identified GPS receiver using the GPS information from the one ormore GPS receiver of the first set of GPS receivers.

In a sixth aspect of the invention, a selective GPS denial systemincludes: a plurality of GPS deniers for disrupting reliable operationof GPS receivers, wherein each of the plurality of GPS deniers may beselectively activated; a plurality of remote sensor interfaces, eachremote sensor interface of the plurality of remote sensor interfacesbeing associated with a respective GPS denier of the plurality of GPSdeniers such that each remote sensor interface effectuates theactivation of a respective GPS denier, wherein the plurality of remotesensor interfaces are communication nodes in an ad hoc wireless network;a gateway, serving as a communication node in the ad hoc wirelessnetwork, that communicates instructions to one or more of the pluralityof remote sensor interfaces to selectively activate the GPS denierrespectively associated therewith; and a computer management system,disposed in communication with the gateway, that controls theinstructions communicated by the gateway, thereby selectivelycontrolling which GPS deniers, of the plurality of GPS deniers, areactivated.

In a feature of this aspect, at least one of the GPS deniers is a GPSjammer, a GPS repeater and/or a GPS signal interruption device.

In another feature of this aspect, each GPS denier of the plurality ofGPS deniers is directly associated with a respective remote sensorinterface of the plurality of remote sensor interfaces. Additionally,each GPS denier and the respective remote sensor interface with which itis directly associated may be integrated into a unitary componentcontained within a single housing, or each GPS denier and the respectiveremote sensor interface with which it is directly associated may bephysically separated from one another and contained in differenthousings. Moreover, each GPS denier and the respective remote sensorinterface with which it is directly associated may be connectedwirelessly, or each GPS denier and the respective remote sensorinterface with which it is directly associated may be connected by wayof a cabled connection.

In yet another feature of this aspect, at least one remote sensorinterface of the plurality of remote sensor interfaces includes astandards based radio. Additionally, the at least one remote sensorinterface includes a Wake-Up Receiver. Moreover, the Wake-Up Receiver isadapted receive a wireless wake-up signal and to activate the standardsbased radio in response thereto, and the gateway includes a Wake-UpTransmitter that is adapted to transmit a wireless wake-up signal toactivate the standards based radio. In this regard, the gateway includesa standards based radio adapted to communicate with the standards basedradio of the at least one remote sensor. Further, the standards basedradio of the at least one remote sensor is adapted to communicate withthe gateway via other remote sensor interfaces using hopping.

In still another feature of this aspect, the computer management systemincludes one or more servers. Further, at least one server may bephysically co-located with the gateway, or at least one server may be acentral server communicatively connected to the gateway via an externalnetwork.

In still another feature of this aspect, the system further includes aGPS receiver, associated with one of the remote sensor interfaces, forreceiving radio signals from GPS satellites and determining parametersbased on the signals received from the GPS satellites, the parametersincluding positional parameters. Further, the GPS receiver is associatedwith the remote sensor interface such that the remote sensor interfaceextracts the GPS parameters from the GPS receiver. The gateway receivesthe extracted GPS parameters from the remote sensor interface, and thecomputer management system receives the extracted GPS parameters fromthe gateway and compares the determined GPS parameters with historicalGPS parameters for the GPS receiver to detect whether an active GPSdenial device is present in the vicinity of the GPS receiver.

In a seventh aspect of the invention, a method for selective GPS denialincludes: disposing at least a portion of a selective GPS denial systemin an area of interest, the selective GPS denial system including (i) aplurality of remote sensor interfaces, each of which is associated witha GPS denier, that form the communication nodes in an ad hoc wirelessnetwork, and (ii) a computer management system that communicatesinstructions to one or more of the plurality of remote sensor interfacesto selectively activate the GPS denier respectively associatedtherewith; determining the location of each of the plurality of remotesensor interfaces within the area of interest; identifying one or moreregions within the area of interest in which GPS denial is desired;transmitting instructions to selected ones of the plurality of remotesensor interfaces, in the identified regions, to activate the respectiveGPS deniers associated therewith; and at each of the selected ones ofthe plurality of remote sensor interfaces, in response to receiving thetransmitted instructions, activating the GPS denier associatedtherewith, thereby causing GPS denial in the identified regions.

In a feature of this aspect, the method further includes the step ofestablishing a corridor of operation in which GPS parameters may bedetermined accurately based on the location of the identified regions.

In an eighth aspect of the invention, a tactical GPS denial/denialdetection system includes: a plurality of GPS detection/denial devices,each having (i) a GPS receiver for receiving radio signals from GPSsatellites and determining parameters based on the signals received fromthe GPS satellites, the parameters including positional parameters, (ii)a GPS denier for disrupting reliable operation of GPS receivers, whereinthe GPS denier may be selectively activated, and (iii) a remote sensorinterface adapted to extract the GPS parameters from the GPS receiverand to effectuate the activation of the GPS denier, (iv) wherein theplurality of remote sensor interfaces are communication nodes in an adhoc wireless network; a gateway, serving as a communication node in thead hoc wireless network, that receives the extracted GPS parameters fromone or more of the plurality of remote sensor interfaces and thatcommunicates instructions to one or more of the plurality of remotesensor interfaces to selectively activate the GPS denier respectivelyassociated therewith; and a computer management system, disposed incommunication with the gateway, that receives the extracted GPSparameters from the gateway and analyzes the GPS parameters to detectwhether an active GPS denial device is present in the vicinity of thesystem, and further that controls the instructions communicated by thegateway, thereby selectively controlling which GPS deniers, of theplurality of GPS deniers, are activated.

In a ninth aspect of the invention, a method of deploying a GPSdenial/denial detection system includes: deploying a plurality of aplurality of GPS detection/denial devices in an area of interest, eachhaving (i) a GPS receiver for receiving radio signals from GPSsatellites and determining parameters based on the signals received fromthe GPS satellites, the parameters including positional parameters, (ii)a GPS denier for disrupting reliable operation of GPS receivers, whereinthe GPS denier may be selectively activated, (iii) a remote sensorinterface adapted to extract the GPS parameters from the GPS receiverand to effectuate the activation of the GPS denier, (iv) wherein theplurality of remote sensor interfaces are communication nodes in an adhoc wireless network; assessing the area of interest for adversarial GPSdenial devices using the plurality of GPS receivers and the ad hocwireless network; based on the assessment, determining a tacticaloperation to be carried out against at least one adversarial GPS denialdevice; and selectively activating, using the ad hoc wireless network,one or more of the plurality of GPS deniers based on the determinedtactical operation.

In a feature of this aspect, the method further includes the step of,after carrying out the determined tactical operation, reassessing thearea of interest for adversarial GPS denial devices using the pluralityof GPS receivers and the ad hoc wireless network.

In another feature of this aspect, the method further includes the stepof establishing a corridor of operation in which GPS parameters may bedetermined accurately based on the locations of the activated GPSdeniers, thereby facilitating tactical operations using the establishedcorridor.

In addition to the aforementioned aspects and features of the presentinvention, it should be noted that the present invention furtherincludes the various possible combinations of such aspects and features.

VI. BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention will be described indetail with reference to the accompanying drawings which are brieflydescribed below, and wherein the same elements are referred to with thesame reference numerals.

FIG. 1 is a block diagram of a GPS denier detection system in accordancewith a preferred embodiment of the present invention;

FIG. 2 is a block diagram of another GPS denier detection system;

FIG. 3 is a block diagram of an exemplary GPS-RSI for use in the systemof FIG. 1;

FIG. 4 is a block diagram of yet another GPS denier detection system;

FIG. 5 is a block diagram of an exemplary gateway for use in the systemof FIG. 1;

FIG. 6 illustrates a first operational mode in which a detection systemis used to detect the presence of a GPS denial device in an area ofinterest;

FIG. 7 illustrates a second operational mode in which a detection systemis used to detect the presence of a GPS denial device in an area ofinterest;

FIG. 8 illustrates a third operational mode in which a detection systemis used to detect the presence or direction of a GPS denial device, inan area of interest, utilizing network assistance in calculating GPSparameters;

FIG. 9 is a block diagram of a GPS denial system in accordance withanother alternative preferred embodiment of the present invention;

FIG. 10 is a block diagram of an exemplary denial RSI for use in thesystem of FIG. 9;

FIG. 11 is a block diagram of an exemplary gateway for use in the systemof FIG. 9;

FIG. 12 illustrates a fourth operational mode in which a GPS deniersystem is used to control selected GPS denier RSIs;

FIGS. 13 and 14 are block diagrams of a combined GPS detection/denialmanagement system in accordance with another preferred embodiment of thepresent invention; and

FIGS. 15-18 illustrate an exemplary seventh operational mode in which acombined GPS detection/denial management system is deployed and utilizedas a tactical measure.

VII. DETAILED DESCRIPTION

As a preliminary matter, it will readily be understood by one havingordinary skill in the relevant art (“Ordinary Artisan”) that the presentinvention has broad utility and application. Furthermore, any embodimentdiscussed and identified as being “preferred” is considered to be partof a best mode contemplated for carrying out the present invention.Other embodiments also may be discussed for additional illustrativepurposes in providing a full and enabling disclosure of the presentinvention. Moreover, many embodiments, such as adaptations, variations,modifications, and equivalent arrangements, will be implicitly disclosedby the embodiments described herein and fall within the scope of thepresent invention.

Accordingly, while the present invention is described herein in detailin relation to one or more embodiments, it is to be understood that thisdisclosure is illustrative and exemplary of the present invention, andis made merely for the purposes of providing a full and enablingdisclosure of the present invention. The detailed disclosure herein ofone or more embodiments is not intended, nor is to be construed, tolimit the scope of patent protection afforded the present invention,which scope is to be defined by the claims and the equivalents thereof.It is not intended that the scope of patent protection afforded thepresent invention be defined by reading into any claim a limitationfound herein that does not explicitly appear in the claim itself.

Thus, for example, any sequence(s) and/or temporal order of steps ofvarious processes or methods that are described herein are illustrativeand not restrictive. Accordingly, it should be understood that, althoughsteps of various processes or methods may be shown and described asbeing in a sequence or temporal order, the steps of any such processesor methods are not limited to being carried out in any particularsequence or order, absent an indication otherwise. Indeed, the steps insuch processes or methods generally may be carried out in variousdifferent sequences and orders while still falling within the scope ofthe present invention. Accordingly, it is intended that the scope ofpatent protection afforded the present invention is to be defined by theappended claims rather than the description set forth herein.

Additionally, it is important to note that each term used herein refersto that which the Ordinary Artisan would understand such term to meanbased on the contextual use of such term herein. To the extent that themeaning of a term used herein—as understood by the Ordinary Artisanbased on the contextual use of such term—differs in any way from anyparticular dictionary definition of such term, it is intended that themeaning of the term as understood by the Ordinary Artisan shouldprevail.

Furthermore, it is important to note that, as used herein, “a” and “an”each generally denotes “at least one,” but does not exclude a pluralityunless the contextual use dictates otherwise. Thus, reference to “apicnic basket having an apple” describes “a picnic basket having atleast one apple” as well as “a picnic basket having apples.” Incontrast, reference to “a picnic basket having a single apple” describes“a picnic basket having only one apple.”

When used herein to join a list of items, “or” denotes “at least one ofthe items,” but does not exclude a plurality of items of the list. Thus,reference to “a picnic basket having cheese or crackers” describes “apicnic basket having cheese without crackers”, “a picnic basket havingcrackers without cheese”, and “a picnic basket having both cheese andcrackers.” Finally, when used herein to join a list of items, “and”denotes “all of the items of the list.” Thus, reference to “a picnicbasket having cheese and crackers” describes “a picnic basket havingcheese, wherein the picnic basket further has crackers,” as well asdescribes “a picnic basket having crackers, wherein the picnic basketfurther has cheese.”

Referring now to the drawings, the preferred embodiments of the presentinvention are next described. The following description of the preferredembodiment(s) is merely exemplary in nature and is in no way intended tolimit the invention, its application, or uses.

FIG. 1 is a block diagram of a GPS denier detection system 10 inaccordance with a preferred embodiment of the present invention. Thedetection system 10 comprises a plurality of remote sensor interfaces,each of which includes a GPS receiver integral therewith (each a“GPS-RSI”) 20, at least one gateway 40, an external network 16 and acomputer management system 14. The GPS-RSIs 20 and the gateway 40 eachcomprise a communication node in one or more ad hoc wireless networks,some of which are described further hereinbelow.

In at least one embodiment, the computer management system 14 primarilyincludes a server, and although different computer management systemarrangements may be utilized, all arrangements will generally bereferred to hereinafter as a “server.” Further, as shown in thedetection system 110 of FIG. 2, the server 14 may be physicallyco-located with the gateway 40, thereby foregoing the need for anexternal network connecting the gateway 40 to the server 14. Thecombination of a gateway 40 with a server 14 in a unitary component issometimes referred to as a “gateway controller.”

Turning now to FIG. 3, a GPS-RSI 20 according to the present inventionis diagrammatically shown to include: a Wake-Up Receiver 22 forreceiving wireless signals, a GPS receiver 24 for calculating theposition of the GPS-RSI 20 and thus the position of the individual orequipment carrying the GPS-RSI 20, a standards based radio 26 fortwo-way wireless communications with, for example, one or more otherGPS-RSIs 20 and/or one or more gateways 40, and an electrical powersource 28, such as a battery. As shown in FIGS. 1 and 3, the GPSreceiver 24 is incorporated directly into the GPS-RSI 20, and as such aseparate interface between the respective devices is not illustrated.Alternatively, a GPS receiver 24 may be physically separated from, butassociated with, the other portions of a GPS-RSI 20, thereby providinggenerally similar functionality to the arrangement depicted in FIGS. 1and 2. Such an arrangement is shown in the detection system 210 of FIG.4. In this regard, the GPS receiver 24 and the other portions of theGPS-RSI 20 may be contained in separate housings, and electroniccommunication between the GPS receiver 24 and the other portions of theGPS-RSI 20 are exchanged wirelessly in some embodiments of the inventionand by way of a cabled connection in other embodiments.

Optionally, the GPS-RSI 20 may further include a sensor interface 30 foracquiring data from one or more sensors associated with the GPS-RSI 20.Insofar as the GPS-RSI 20 is associated with military equipment andpersonnel assets, such individual soldiers, operational units orvehicles or other equipment carrying or supporting personnel orequipment, the GPS-RSI 20 preferably is capable of interfacing withsensors that, for example, monitor the assets, environmentalcharacteristics of the assets, and/or geographical locations of theassets. In some embodiments, such sensors may actually be includedwithin the GPS-RSI 20; in other embodiments, such sensors may beexternal to the GPS-RSI 20 but nevertheless disposed in electroniccommunication with the sensor interface for data exchange therebetween.Electronic communication between the sensor interface and a sensor isexchanged wirelessly in some embodiments of the invention and by way ofa cabled connection in other embodiments. In at least one embodiment,the sensor interface comprises a multi-conductor connector, such as aribbon cable, that passes from the interior of an GPS-RSI 20 and to anexternal sensor, sensor array, or docking station that receives theGPS-RSI 20. Exemplary sensors include, but are not limited to,electronic seals, magnetic seals, cameras, microphones, temperaturesensors, humidity sensors, radiation sensors, and motion sensors.

In order to reduce unnecessary power consumption, the standards basedradio 26, which has a relatively high power consumption rate whenactive, is generally dormant until awakened. The Wake-Up Receiver 22,which has a relatively low power consumption rate compared to that ofthe standards based radio 26, generally remains active for detectingincoming wireless wake-up signals. Upon receipt of a wake-up signalintended for the GPS-RSI 20, the Wake-Up Receiver 22 generally wakes-upthe standards based radio 26 for receiving and transmitting data via thestandards based radio 26. Those components of the GPS-RSI 20 thatconsume relatively high amounts of power thereby are generally activeonly when needed.

The Wake-up Receiver 22 includes components for receiving wirelesswake-up signals. The Wake-Up Receiver 22 is generally similar infunction to the “WT Component” described in detail, for example, inincorporated International Patent Application Publication No. WO03/098851 A1 (and which international application entered the U.S.national phase and published as U.S. Patent Application Publication No.US 2005/0215280, also incorporated herein by reference). The Wake-UpReceiver 22 moreover has been occasionally referred to as a “tag turn-oncircuit,” a “TTOC” or a “Wake-Up Rx.” The process for determiningwhether to wake-up the standards based radio of the GPS-RSI 20furthermore may include a number of steps that are performed in aparticular sequence, especially if the GPS-RSI 20 is disposed in a noisyradio-frequency (RF) environment. For example, such a wake-up sequenceis described in the disclosure of U.S. patent application Ser. No.11/421,321, which published as U.S. Patent Application Publication No.2006/0269633, each of which is hereby incorporated herein by reference.

Reduction in unnecessary power consumption may also be achieved byutilizing common designation ad hoc networks such as, for example,class-based networks. Common designation networking is disclosed, forexample, in U.S. patent application Ser. No. 11/161,539, which publishedas U.S. Patent Application Publication No. 2006/0023678 A1, each ofwhich is hereby incorporated herein by reference.

Turning now to FIG. 5, a gateway 40 may include: a Wake-Up Transmitter42 for transmitting wireless signals, a standards based radio 26 fortwo-way wireless communications with one or more GPS-RSIs 20 and/or oneor more other gateways 40, and an electrical power source 48, such as abattery. The gateway 40 may also include a GPS receiver 24 forcalculating the position of the gateway 40 and/or a sensor interface 30for acquiring data from one or more sensors associated with the gateway40.

The Wake-Up Transmitter 42 includes components for transmitting wirelesswake-up signals. The Wake-Up Transmitter 42 has occasionally beenreferred to as a “tag turn-on,” a “TTO” or a “Wake-Up Tx,” and theWake-Up Transmitter 42 is capable of sending signals to Wake-UpReceivers 22, TTOCs, or the like, for wake-up of GPS-RSIs 20. In atleast one other embodiment (not shown), a gateway may include a Wake-UpReceiver 22 like those included in the GPS-RSIs 20, either in place ofor in addition to the Wake-Up Transmitter. In this embodiment, theWake-Up Transmitter is further capable of sending signals to gateways40.

The gateway 40 facilitates communication between one or more wirelessnetworks, formed using the gateway 40 and one or more of the GPS-RSIs 20as communication nodes, and the external network 16. As such the gateway40 further includes one or more appropriate connections forcommunicating with such an external network 16, such connectionincluding but not limited to a network interface for mobile phone, WiFi,two-way radio, secure radio links, Ethernet, and/or satellitecommunications. Each gateway 40 thus serves as an access point forcommunications with the external network 16. Electronic communicationbetween the network interface and the external network 16 may beexchanged wirelessly in some embodiments of the invention and by way ofa cabled connection in other embodiments.

The external network 16 may include wired or wireless communicationsusing any of the foregoing technologies or combination thereof, as wellas any other appropriate communication technologies. Additionally, theexternal network 16 may incorporate use of the Internet or some otherwide area network.

The GPS-RSIs 20 are programmed to communicate directly with the gateway40 or to communicate via hopping. Because the GPS-RSIs 20 can hopbetween one another to reach a gateway 40, fewer gateways 40 are neededto cover an area. The gateway 40 communicates with the server 14, whichis disposed on and/or connected to the external network 16.

The server 14 is responsible for numerous functions in detecting thepresence of a GPS denial device. For example, as described below, theserver 14 extracts GPS parameters from each GPS-RSI 20 and compares suchextracted parameters with historical parameters. The server 14 also actsas an application interface and provides control for the GPS receivers24 and any other sensors communicatively connected to a GPS-RSI 20 viasensor interface 30.

Some of the components of the detector system 10 are disclosed infurther detail in the incorporated references. In at least someembodiments, the present invention relates to use of such components inimplementations involving GPS denier detection and/or selective GPSjamming.

Advantageously, the system of FIG. 1 has the ability to determine ordetect whether a GPS denial device is present so that it can beidentified and knocked out by military action and has the ability tofind a GPS denial device based on the effect that it is having onmultiple GPS receivers disposed in a particular area.

An RSI with an associated GPS receiver is relatively inexpensive and maybe housed within a relatively small form factor. Accordingly, suchRSI-GPS receiver combinations may be deployed on a large scale due tothe relatively low expense and size of the combination. Further, thesmall size renders the combination relatively inconspicuous and easilydisguisable, which is particularly advantageous in militaryapplications.

FIGS. 6-9 are block diagrams of detector systems in accordance withmultiple preferred operational modes of a system of the presentinvention. For example, FIG. 6 illustrates a first operational mode inwhich a detection system 10 is used to detect the presence of a GPSdenial device 60 in an area of interest 50. In the first operationalmode, the detection system 10 once again comprises a plurality ofGPS-RSIs 20, a gateway 40, an external network (not shown) and a server(not shown). As shown, the GPS-RSIs 20 and the gateway 40 are thecommunication nodes of an ad hoc wireless network.

In operation, the system of FIG. 6 is able to detect the presence of theGPS denial device 60 as follows. On an ongoing basis, the GPS receivers24 accept GPS radio signals from GPS satellites (not shown). Based onsuch signals, the GPS receivers 24 determine positional parameters suchas latitude, longitude, and altitude. GPS receivers 24 may alsodetermine, or be used to determine, parameters such as signal velocity,signal strength, satellites in view, and various other informationrelated to received GPS radio signals. A microprocessor or the like (notshown) in each GPS-RSI 20 extracts the available parameters from the GPSreceiver 24 associated therewith and the GPS-RSI 20 uses its standardsbased radio 26 to communicate the parameters to the server 14 via thegateway 40 and external network 16. If the GPS-RSI 20 is unable tocommunicate directly with the gateway 40, conventional hoppingtechniques may be used to communicate the parameters to the gateway 40via one or more intermediate GPS-RSIs 20. As the server 14 receives GPSparameters from the GPS receivers 24 of the various GPS-RSIs 20, asoftware application stores the parameters in an appropriate locationand format for later retrieval and examination.

GPS parameter data is preferably gathered on a regular basis, with thefrequency being selected on the basis of one or more factors, such asaccuracy, speed, bandwidth, data capacity, and the like. In thepreferred embodiment, GPS parameter data is gathered at a frequencycontrolled by the server 14 using the Wake-Up Transmitters 42 andWake-Up Receivers 22 to awaken the various GPS-RSIs 20 as desired. Morespecifically, when the server 14 (or the software application beingexecuted thereon) determines that it is time to receive GPS parameterdata from the GPS receiver 24 of a GPS-RSI 20, the server 14 may controlone or more gateways 40 to transmit, via their respective Wake-UpTransmitters 42, a wake-up signal appropriate to awaken the GPS-RSI 20.Such signals may be tailored to awaken a particular GPS-RSI 20, allGPS-RSIs 20 in a wireless network, or any subset thereof, as desired.Upon receiving such a wake-up signal, the Wake-Up Receiver 22 of theGPS-RSI 20 causes the GPS receiver 24 and the standards based radio 26to awaken, and the GPS receiver 24 is set into listening mode. After asufficient duration has passed for the GPS receiver 24 to gather radiosignal information, the desired parameters are read out of the GPSreceiver 24 and transmitted by the standards based radio 26 for relayback to the server 14 for analysis.

If the gateway 40 is equipped with its own GPS receiver 24, then GPSparameters from the gateway GPS receiver 24 may likewise be gathered andrelayed back to the server 14. In this regard, it may be desirable forthe gateway 40 to be likewise equipped with a Wake-Up Receiver 22 inorder to conserve power or to simplify operation of the system 10.

Optionally, other techniques or criteria may be used to awaken a GPS-RSI20 or gateway 40. For example, other devices, such as a real-timeclocks, or sensor triggers such as those based on motion, temperature,or humidity and optionally gathered via the sensor interface 30, canalso awaken the GPS-RSIs 20. Notably, with the wake-up technologiesdescribed above, radio standby time and receive mode currents no longerdrive battery requirements. Further, battery power is actually conservedbecause the GPS-RSI 20 has the ability to enable event-driven monitoringof GPS receivers 24.

Parameters extracted from the receivers 24 at any particular time can becompared to previously extracted, historical parameters, which arestored at the server, to deduce whether a jammer 60 is present. Morespecifically, algorithms may be used to determine when newly-receivedGPS parameter data is likely corrupted by the operation of a nearby GPSdenial device 60. If the server 14 determines that a GPS denial device60 appears to be present in the vicinity of a GPS-RSI 20, appropriateinformation may be relayed back to the GPS-RSI 20, to one or more otherGPS-RSIs 20, to other nearby equipment (not shown), or in any other wayappropriate for notifying the equipment and/or a user as to the presenceof a GPS denial device 60 operating nearby. In addition, oralternatively, appropriate information may be relayed to unrelatedpersonnel or equipment in any location. For example, in militaryoperations, if a GPS denial device 60 is discovered, it may be desirableto order an air strike targeting the GPS denial device 60.

FIG. 7 illustrates a second operational mode in which a detection system10 is used to detect the direction of a GPS denial device 60 in an areaof interest 50. In the second operational mode, the detection system 10once again comprises a plurality of GPS-RSIs 20, a gateway 40, anexternal network (not shown) and a server (not shown), and as shown, theGPS-RSIs 20 and the gateway 40 are the communication nodes of an ad hocwireless network.

GPS denial devices 60 tend to be directional, so information about thestatus of GPS receivers 24 and their relative positions can be used todetermine the location of a GPS denial device 60. More particularly, thedifficulty encountered by the GPS receiver 24 in calculating an accurateposition may be used as a rough indicator of the proximity of a GPSdenial device 60. For example, if the server 14 determines, based on acomparison of current GPS parameter data to historical GPS parameterdata, that a GPS receiver 24 is denied or prevented from calculating aposition altogether, the likelihood of a GPS denial device 60 beingrelatively near that GPS-RSI 20 is high. If the server 14 determinesthat a GPS receiver 24 is able to calculate a partial position or aposition close to its previously-determined, historical, position, theGPS receiver 24 is likely farther away from the GPS denial device 60.

In this regard, FIG. 7 illustrates a first region (“Region A”) 52,defined generally as a region in which GPS receivers 24 is denied orprevented from calculating a position altogether, and a second region(“Region B”) 54, defined generally as a region in which GPS receivers 24are able to calculate at least a partial position but for which thecalculation is adversely affected by a GPS denial device 60. The GPS-RSI20 labeled “G-R #2” is shown to be disposed in Region A 52, while theGPS-RSIs 20 labeled “G-R #3” and “G-R #4” are shown to be disposed inRegion B 54.

Using this phenomenon, recent positional parameters can thus be comparedto previously determined positional parameters to determine the generaldirection of a GPS denial device 60. More specifically, the generaldirection of a GPS denial device 60 may be visualized by drawing animaginary arrow 56 starting from a GPS receiver 24 with a partiallyerroneous position (such as “G-R #3” and “G-R #4”) and drawn through toa GPS receiver 24 (such as “G-R #2”) that is denied a positioncalculation altogether. Such an arrow 56 points generally in thedirection of the GPS denial device 60. Other GPS parameters can bestudied to determine likely proximity of a GPS receiver 24 relative to aGPS denial device 60, thereby providing a distance estimate in additionto a directional estimate. Similar techniques can be used if the radioreceiver is something other than a GPS receiver 24.

FIG. 8 illustrates a third operational mode in which a detection system10 is used to detect the presence or direction of a GPS denial device60, in an area of interest 50, utilizing network assistance incalculating GPS parameters. Such an operational mode may be useful incertain environments, such as urban environments, jungle canopy,mountainous regions and high multi-path environments, in which standardGPS receivers 24 frequently have difficulty generating accurate GPSparameters independently.

In this operational mode, the detection system 10 once again comprises aplurality of GPS-RSIs 20, a gateway 40, an external network (not shown)and a server (not shown), and as shown, the GPS-RSIs 20 and the gateway40 are the communication nodes of an ad hoc wireless network. Pertinentinformation such as Ephemeris, Almanac, GPS time, approximate location,satellites that should be in view, and the like is determined by a GPSreceiver 24 known to be reliable, such as a GPS receiver 24 located at agateway 40 known to be uncompromised and uncorrupted, and/or provided bythe server 14. Using the standards based radios 26 on the respectivedevices, the information thus developed is then downloaded from thegateway 40 to the GPS-RSI 20 that is encountering difficulty indetermining GPS parameters accurately.

Using the downloaded information, the GPS receiver 24 may then be ableto calculate its position and other GPS parameters accurately withoutrelying solely on the GPS radio signals it receives from the GPS system.If so, then the GPS parameters may be relayed back to the server 14 asdescribed previously, and using the newly-calculated GPS parameters ashistoric data, the GPS receiver 24 may then be restarted to determinethe effects, if any, of a GPS denial device 60.

FIG. 9 is a block diagram of a GPS denial system 70 in accordance with apreferred embodiment of the present invention. The detection system 70comprises a plurality of remote sensor interfaces, each of whichincludes a GPS denier 84 integral therewith (each a “denial RSI”) 80, atleast one gateway 90, an external network 16 and a computer managementsystem 14. The denial RSIs 80 and the gateway 90 each comprise acommunication node in one or more ad hoc wireless networks, some ofwhich are described further hereinbelow.

The computer management system or server 14 and external network 16 maybe similar to those of FIG. 1, described above, except that the computermanagement system (again referred to generally as a “server”) 14 hasdifferent or additional functionality as described below. Also, as withthe system 10 of FIG. 1, the server 14 may be physically co-located withthe gateway 90, thereby foregoing the need for the external network, andthe combination of a gateway 90 with a server 14 in a unitary componentis sometimes referred to as a “gateway controller.”

Turning now to FIG. 10, a denial RSI 80 according to the presentinvention is diagrammatically shown to include: a Wake-Up Receiver 22for receiving wireless signals, a GPS denier 84 for jamming enemy GPSreceivers (not shown), a standards based radio 26 for two-way wirelesscommunications with, for example, one or more other denial RSIs 80and/or one or more gateways 90, and an electrical power source 28, suchas a battery. As shown in FIGS. 10 and 11, the GPS denier 84 isincorporated directly into the denial RSI 80, and as such a separateinterface between the respective devices is not illustrated. Althoughnot shown, a GPS denier 84 alternatively may be physically separatedfrom, but associated with, the other portions of a denial RSI 80,thereby providing generally similar functionality to the arrangementdepicted in FIG. 10. In this regard, the GPS denier 84 and the otherportions of the denial RSI 80 may be contained in separate housings, andelectronic communication between the GPS denier 84 and the otherportions of the denial RSI 80 are exchanged wirelessly in someembodiments of the invention and by way of a cabled connection in otherembodiments.

As with the GPS-RSI 20, the denial RSI 80 may further include a sensorinterface 30 for acquiring data from one or more sensors associated withthe denial RSI 80. The sensor interface 30 is similar to, and providessimilar functionality as, the sensor interface 30 of the GPS-RSI 20. Thestandards based radio 26 and Wake-Up Receiver 22 are also similar tothose of the GPS-RSI 20, and like the GPS-RSI 20, reduction inunnecessary power consumption may also be achieved by utilizing commondesignation ad hoc networks such as, for example, class-based networks.

Turning now to FIG. 11, a gateway 90 may include: a Wake-Up Transmitter42 for transmitting wireless signals, a standards based radio 26 fortwo-way wireless communications with one or more denial RSIs 80 and/orone or more other gateways 90, and an electrical power source 48, suchas a battery. The gateway 90 may also include a GPS denier 84 forjamming enemy GPS receivers and/or a sensor interface 30 for acquiringdata from one or more sensors associated with the gateway 90. Other thanthe GPS denier 84, the components of the gateway 90 may be generallysimilar to the corresponding components of the gateway 40 of FIG. 5.

In like manner to the gateway 40 of FIG. 5, the gateway 90 of FIG. 11facilitates communication between one or more wireless networks, in thiscase formed using the gateway 90 and one or more of the denial RSIs 80as communication nodes, and the external network 16. As such the gateway90 once again further includes one or more appropriate connections forcommunicating with such an external network 16, such connectionincluding but not limited to a network interface for mobile phone, WiFi,two-way radio, secure radio links, Ethernet, and/or satellitecommunications. Like the gateway of FIG. 5, each gateway 90 thus servesas an access point for communications with the external network 16.Electronic communication between the network interface and the externalnetwork 16 may once again be exchanged wirelessly in some embodiments ofthe invention and by way of a cabled connection in other embodiments.

The denial RSIs 80 are programmed to communicate directly with thegateway 90 or to communicate via hopping. Because the denial RSIs 80 canhop between one another to reach a gateway 90, fewer gateways 90 areneeded to cover an area. The gateway 90 communicates with the server 14,which in at least one embodiment is disposed on and/or connected to theexternal network 16, and in at least another embodiment is physicallyco-located with the gateway 90 as stated previously.

The server 14 is responsible for numerous functions in controlling theoperation of the GPS deniers 84. For example, as described below, theserver 14 may send messages or signals to the gateway 90, or to thedenial RSIs 80 via the gateway 90, to activate or deactivate one or moreof the respective GPS deniers 84. In this regard, common designationnetworks may be utilized to control one GPS denier 84 or gateway 90, allthe GPS deniers 84 and gateways 90, or any subset thereof. The server 14may also track location information about the respective denial RSIs 80and/or gateway 90, thereby facilitating the localized use of therespective GPS deniers 84 as desired. In this regard, GPS parameters maybe used to track the location of the denial RSIs 80 and gateway 90. SuchGPS parameters may be developed, for example, but not limited to,through the use of GPS receivers located at or near the denial RSIs 80and/or gateway 90. In this regard, GPS receivers such as the GPSreceivers 24 described above may be associated with the respectivedenial RSIs 80 as described hereinbelow.

FIG. 12 illustrates a fourth operational mode in which a GPS deniersystem 70 is used to control selected denier RSIs 80 so as to create acorridor of reliable GPS operation, in an area of interest 50, that isfree from the effects of friendly GPS deniers 84. In the fourthoperational mode, the detection system 70 once again comprises aplurality of denier RSIs 80, a gateway 90, an external network (notshown) and a server (not shown), and as shown, the denier RSIs 80 andthe gateway 90 are the communication nodes of an ad hoc wirelessnetwork.

In FIG. 12, the denier RSIs 80 labeled “DENIER-RSI #1” and “DENIER-RSI#5” are shown to have active GPS deniers 84, while the remaining denierRSIs 80 are shown in thave inactive GPS deniers 84. As such, a corridorof reliable GPS operation, represented generally by arrows 58, is shownto exist in the region between the respective ranges of operation of“DENIER-RSI #1” and “DENIER-RSI #5.” Localized GPS denial is thusprovided in the regions around “DENIER-RSI #1” and “DENIER-RSI #5” whiletroop movement, such as in the direction of the arrows 58, is permittedthrough the corridor, without GPS receivers carried by such troops beingaffected by those deniers 84. As stated previously, the selection ofparticular denial RSIs 80 to be activated or deactivated may becontrolled by the server 14, and the locations of the denial RSIs 80 arepreferably tracked by the server 14 so as to provide useful locationalinformation to friendly parties as appropriate.

Significantly, one or more aspects of a GPS detection system 20 and aGPS denier system 70 may be combined in a single GPS detection anddenial management system 110, as represented in FIGS. 13-17. Optionally,but not necessarily, such a system 110 may make use of combined GPSdetection/denial RSIs 120 and/or combined GPS detection/denial-equippedgateways 140. Combined GPS detection/denial RSIs 120 include both a GPSreceiver 24 and a GPS denier 84, as those components are describedpreviously, and combined GPS detection/denial-equipped gateways 140likewise include both a GPS receiver 24 and a GPS denier 84, wherein therespective GPS receiver 24 and a GPS denier 84 may be operatedindependently, preferably under the control of a server 14. Furthermore,such a system 110 may include multiple gateways 40, 90, 140, each ofwhich may be connected to the server 14 via an external network 16.

FIGS. 13 and 14 are block diagrams of a combined GPS detection/denialmanagement system 120 in accordance with another preferred embodiment ofthe present invention. More particularly, FIG. 13 illustrates a fifthoperational mode in which GPS-equipped RSIs 20, 120 and GPS-equippedgateways 40, 140 form ad hoc wireless networks that are separate from adhoc wireless networks formed by GPS denier-equipped RSIs 80, 120 and GPSdenier-equipped gateways 90, 140, while FIG. 14 illustrates a sixthoperational mode in which ad hoc wireless networks are formed thatinclude GPS-equipped RSIs 20, 120, GPS denier-equipped RSIs 80, 120,GPS-equipped gateways 40, 140 and GPS denier-equipped gateways 90, 140.In each operational mode, it is assumed that one or more enemy GPSdenial devices 60 are operating in the vicinity of the system 120. InFIG. 13, the combined GPS detection/denial-equipped gateway 140 and afirst of the GPS denier-equipped RSIs 80 have been activated, while inFIG. 14, the combined GPS detection/denial-equipped gateway 140 and thefirst GPS denier-equipped RSI 80 have been deactivated, while a secondGPS denier-equipped RSI 80 and the combined GPS detection/denial RSI 120have been activated.

Notably, communications between the various devices 20, 40, 80, 90, 120,140 are maintained, via their respective standards based radios 26,regardless of whether the respective associated GPS receivers 24 arebeing jammed or otherwise disrupted. Further, it will be appreciatedthat in at least one embodiment, the fifth and sixth operational modesare merely variations of the same operational mode, wherein the types ofdevices that are included in a particular ad hoc network may becontrolled using different designations in a common designation ad hocnetwork, as described previously.

FIGS. 15-18 illustrate an exemplary seventh operational mode in which acombined GPS detection/denial management system 120 is deployed andutilized as a tactical measure. Such a deployment methodology may beutilized, for example, when it is desired to search an area of interestfor enemy GPS denial devices 60 for the purpose of identification andpossible tactical measures against the GPS denial devices 60, or when ithas already been established that such devices 60 are operating andadditional identification and possible tactical measures are desired. Asshown in FIG. 15, gateways, such as combined GPSdetection/denial-equipped gateways 140, may be set up in the area ofinterest, or, if available, pre-existing gateways may be utilized. Next,as shown in FIG. 16, a multitude of GPS-equipped RSIs, which arepreferably combined GPS detection/denial RSIs 120, are deployed in thearea of interest. Deployment may be achieved via air drop, by landvehicle, by personnel traveling on foot, or by any combination thereof.Pre-existing RSIs, including any combination of RSI devices 20, 80, 120,may likewise be utilized.

Once deployed, each of the GPS-equipped RSIs 120 may be activated (ifnot previously activated) via one or more ad hoc wireless networks, asshown in FIG. 17, and GPS parameters from the various GPS receivers 24,in both the RSIs 120 and the gateways 140, may be transmitted back tothe gateways 140. The GPS parameters are then communicated via theexternal network to the server (not shown). As will be apparent, hoppingmay be used to transmit the GPS parameters from more remotely-locatedRSIs 120 back to the various gateways 140. If deployment has beensuccessful, some of the GPS-equipped RSIs 120 are within range of theenemy GPS denial devices 60, while others are located out of range ofsuch devices 60. The server 14 assesses all of the GPS parameter data,determining which RSIs 120 and which gateways 140 are within thevicinity of a GPS denial device 60 and where such GPS denial devices 60are likely to be located. Such determinations may be accomplished usingthe techniques described hereinabove, including vicinity assessment,direction assessment, and network-aided correction and assessment. Theserver 14 is preferably capable of accumulating and combining allinformation thus developed. Further, the server 14 may provide variousgraphical user interfaces (“GUIs”) and/or other user interfaces (“UIs”)that may assist user in locating the GPS denial devices 60 and tacticalplanning with regard an appropriate response to such GPS denial devices60. As described previously, the server 14 may also provide appropriateinformation back to one or more of the RSIs 120, gateways 140, and/orother personnel, equipment, and the like.

As information about the location of the enemy GPS denial devices 60 isdeveloped, an appropriate tactical response may likewise be developed.As shown in FIG. 18, some of the GPS deniers 84 may be activated, whileothers remain deactivated. Selection of GPS deniers 84 to be activatedmay be based on the tactical response chosen for dealing with the enemyGPS denial devices 60. The tactical response may include operationsintended to destroy one or more enemy GPS denial devices 60, to disruptoperation of one or more enemy GPS denial devices 60 using electronictechniques and the like, or other tactical strategies. An example of anelectronic technique is the use of conventional signal cancellationtechniques, where a signal that is an exact inversion of a jammingsignal produced by an enemy GPS denial device 60 is transmitted, therebyeffectively destroying the jamming signal.

Further, in order to inhibit reliable operation of enemy GPS receiversthat may be active in the area of interest, while at the same timepermitting continued movement or operation of friendly forces in certainregions of the area of interest, using unaffected GPS receivers, the GPSdeniers 84 that are activated may be selected in order to achievetightly-controlled corridors between the zones of coverage of both enemyand friendly GPS denial devices 60, 84. Such a corridor or region isillustrated in FIG. 18, extending from the lower left corner of the areaof interest into the center of the area, and further extending from thecenter of the area toward the right-hand side of the area. GPS receiversin the corridor may accurately make position determinations. Thecorridor thus permits free movement or operation, using reliable GPSdeterminations, as part of a direct tactical response to the enemy GPSdenial devices 60 as well as unrelated movement or operation by friendlyforces. In summary, this technique, multiple GPS deniers 84 may bedeployed with associated RSIs to create a patchwork of GPS deniers 84 tofit situational needs. Advantageously, precise deployment and control ofGPS deniers 84 allows defined areas to be selected for jamming withouthaving to deny GPS access to a larger area.

With further regard to deployment tactics, other related approachesinclude putting GPS receivers 24 on robots, drones or other machinesthat can be moved throughout an area of interest. The GPS receivers 24can be replaced with any radio receiver to determine the jamming effectson a receiver in an “area of interest”. Parameters from each of thesereceivers 24 may be different, but the comparison of the parameters bythe associated server 14 enables the system 110 to determine the extentof the jamming.

In addition to the advantages described previously herein, the presentinvention also provides benefits such as the ability to determine thetype of GPS denial device 60 so that corrections can be made in theactual position, and improved sensitivity and diversity making detectionof GPS denial devices 60 more robust.

The techniques described herein may also be used to measure theeffectiveness of actions to remove known GPS denial devices 60. Throughan iterative process, a system 110 such as that of FIGS. 15-18 can beutilized to repeatedly search an area of interest for adversarial GPSdenial devices 60 after one or more tactical actions have been taken.This step can measure the effectiveness of the tactical operation bydetermining whether or not the adversarial GPS denial devices 60 arestill in operation. The step can also be help identify the presence andlocation of additional GPS denial devices 60 that had not beenpreviously detected.

Any of the gateways 40, 90, 140 described herein may also oralternatively be carried on an airborne platform, such as an UnmannedAerial Vehicle (UAV), airship, airplane, or the like. In this scenario,the gateway 40, 90, 140 would communicate to the various RSIs 20, 80,120 or land-based gateways 40, 90, 140 via wireless LAN (Local AreaNetwork) and communicate over a satellite back to a remote server 14. Inat least one embodiment, a gateway controller (comprised of a gateway40, 90, 140 and a server 14) can also be mounted on the aerial platformand potentially provide database updates remotely.

Notably, at least some of the techniques described herein for locatingenemy GPS denial devices 60 may likewise be utilized to identify monitorregions in which GPS reception is affected by friendly GPS deniers 84,to provide feedback regarding the effects of friendly GPS denialattempts, and the like.

Based on the foregoing description, it will be readily understood bythose persons skilled in the art that the present invention issusceptible of broad utility and application. Many embodiments andadaptations of the present invention other than those specificallydescribed herein, as well as many variations, modifications, andequivalent arrangements, will be apparent from or reasonably suggestedby the present invention and the foregoing descriptions thereof, withoutdeparting from the substance or scope of the present invention.

Accordingly, while the present invention has been described herein indetail in relation to one or more preferred embodiments, it is to beunderstood that this disclosure is only illustrative and exemplary ofthe present invention and is made merely for the purpose of providing afull and enabling disclosure of the invention. The foregoing disclosureis not intended to be construed to limit the present invention orotherwise exclude any such other embodiments, adaptations, variations,modifications or equivalent arrangements, the present invention beinglimited only by the claims appended hereto and the equivalents thereof.

1. A system for operating a GPS receiver in a GPS-adverse environment,comprising: (a) a plurality of GPS receivers for receiving radio signalsfrom GPS satellites, wherein each of the plurality of GPS receivers isadapted to determine parameters for itself based on the signals receivedfrom the GPS satellites, the parameters including positional parameters,wherein at least one of the GPS receivers, defining a first set of GPSreceivers, is able to accurately determine its positional parameters andat least one other of the GPS receivers, defining a second set of GPSreceivers, is unable to determine its positional parameters accurately;(b) a plurality of remote sensor interfaces, each remote sensorinterface of the plurality of remote sensor interfaces being associatedwith and in electronic communication with a respective GPS receiver ofeither the first set or second set of GPS receivers such that eachremote sensor interface is adapted to extract the GPS parameters from arespective GPS receiver, wherein the plurality of remote sensorinterfaces are communication nodes in an ad hoc wireless network suchthat each of said plurality of remote sensor interfaces is in electroniccommunication with the other remote sensor interfaces of the pluralityof remote sensor interfaces; and (c) a computer management system thatidentifies a GPS receiver that is not accurately determining itspositional parameters, and in response, causes GPS information to beprovided from a selected GPS receiver in the first set of GPS receiversto the identified GPS receiver; (d) whereby the identified GPS receiveris adapted to determine its positional parameters accurately using atleast the GPS information provided from the selected GPS receiver in thefirst set of GPS receivers.
 2. The system of claim 1, wherein thecomputer management system is co-located with the identified GPSreceiver at the remote sensor interface associated therewith.
 3. Thesystem of claim 1, wherein the computer management system is co-locatedwith the selected GPS receiver, of the first set of GPS receivers, atthe remote sensor interface associated therewith.
 4. The system of claim1, wherein the computer management system is located remotely from theremote sensor interfaces.
 5. The system of claim 1, further comprising agateway, serving as a communication node in the ad hoc wireless network,that is adapted to receive the extracted GPS parameters from one or moreof the plurality of remote sensor interfaces.
 6. The system of claim 5,wherein the computer management system is co-located with the gateway.7. The system of claim 1, wherein the computer management system isadapted to identify the GPS receiver that is not accurately determiningits positional parameters by receiving the extracted GPS parameters fromthe identified receiver and comparing the determined GPS parameters withhistorical GPS parameters for the identified GPS receiver.
 8. The systemof claim 1, wherein the GPS information includes at least one ofEphemeris information, Almanac information, GPS time information,approximate location information, and information on GPS satellites thatshould be in view of the identified GPS receiver.
 9. The system of claim1, wherein each remote sensor interface includes a standards based radioadapted for transmitting and receiving the GPS information.
 10. Thesystem of claim 9, wherein the at least one remote sensor interfaceincludes a Wake-Up Receiver.
 11. The system of claim 10, wherein theWake-Up Receiver is adapted to receive a wireless wake-up signal and toactivate the standards based radio in response thereto.
 12. A method fordetermining a location of a GPS receiver in a GPS-adverse environment,comprising: (a) providing a plurality of GPS receivers, each interfacedwith a respective remote sensor interface, the remote sensor interfacesbeing communication nodes in an ad hoc wireless network; (b) determiningthe locations of a first set of GPS receivers using radio signalsreceived from GPS satellites; (c) communicating GPS information, via thead hoc wireless network, from one or more GPS receivers of the first setof GPS receivers to an identified GPS receiver that is unable todetermine GPS parameters from GPS radio signals received from GPSsatellites; and (d) determining the location of the identified GPSreceiver using the GPS information from the one or more GPS receivers ofthe first set of GPS receivers.